Colorectal cancer holds an uncomfortable distinction in Singapore: it is the single most common cancer among men, and the second most common among women after breast cancer. It is also, in the words of gastroenterologist Dr. Prem H. Thurairajah, one of the few cancers that can often be prevented outright — not just detected early, but stopped before it develops into cancer.
“Colorectal cancer is the second commonest cancer affecting Singaporeans,” Dr. Prem explains, “and increasingly we are seeing a rise in the number of colorectal cancer cases amongst people below the age of 50.” This trend is borne out in national data: Singapore Cancer Registry figures show that early-onset colorectal cancer, diagnosed in adults under 50, has been rising for decades, with Malay and Chinese populations showing particularly notable increases in certain age groups. Colorectal cancer is no longer a disease that can be safely filed away as “something that happens to older people.”
What makes this cancer distinctive is not just how common it is, but how well understood its origins are. Unlike many cancers that arise with little warning, colorectal cancer almost always follows a long, slow, and, crucially, interruptible path. Understanding that path is the starting point for understanding why screening works, and why Dr. Prem is so direct about urging Singaporeans not to delay it.
Almost all colorectal cancers begin as polyps, small, benign growths on the inner lining of the bowel.
“Polyps are benign lesions which affect the bowel, which eventually can grow and become cancerous over time,” Dr. Prem explains. On their own, polyps are harmless. Left alone for long enough, however, some polyps accumulate genetic changes that allow them to become malignant.
“It usually takes about 10 to 15 years for colonic polyps to grow and turn malignant,” Dr. Prem adds.
That decade-long window is perhaps the most important fact about colorectal cancer. It means that, for the vast majority of people, colorectal cancer is not a sudden event but the end point of a slow process that was, at multiple earlier stages, entirely preventable.
A polyp identified and removed during a screening colonoscopy simply never gets the chance to become cancerous. In a session, the disease is stopped at its earliest, most treatable stage.
“Testing and detecting these polyps early is the surest way of reducing colorectal cancer,” Dr. Prem notes. It is precisely why Singapore's Ministry of Health recommends that screening begin at age 50 for those at average risk. It is timed to catch polyps that have had years to develop, well before they have had the decade or more typically needed to progress.
If colorectal cancer can, in a number of cases, be prevented rather than merely treated, you might ask: why do rates in the community remain so high? The answer, according to Dr. Prem, has less to do with medicine and more to do with human behaviour.
“Only 33% of people take up screening,” Dr. Prem notes. “That means only 1 in 3 people who should be screened are actually getting screened.”
Two in three people who should be screened for colorectal cancer in Singapore simply are not being screened. Dr. Prem is candid about why that may be the case: “A lot of people feel uncomfortable addressing this issue. A lot of it is borne by fear.”
This discomfort is understandable. After all, screening involves a part of the body that isn't often discussed openly, and the tests themselves can sound intimidating before they're properly understood. The second, quieter barrier is the misconception about colorectal cancer symptoms. Many people may reason that if nothing feels wrong, there is nothing to screen for.
Dr. Prem addresses this directly, “Some people feel that if they don't have any symptoms, then there isn't a problem. But in reality, colonic polyps don't cause any symptoms.”
This is the key challenge of colorectal cancer screening, the disease is most preventable at exactly the stage when it is least likely to announce itself. Waiting for symptoms before getting screened defeats the purpose of screening. Since by the time symptoms appear, the disease has often already progressed well beyond the polyp stage.
Screening recommendations in Singapore are not one-size-fits-all. They are calibrated to an individual's health risks, and starting earlier matters significantly for those with elevated risk factors.
For people at average risk with no family history, colorectal cancer screening is recommended from age 50, according to Ministry of Health guidelines. For those with a family history of colorectal cancer, screening should begin earlier, from age 40. Individuals with a genetic predisposition, such as Lynch syndrome, should start screening even earlier, from their mid-20s.
“Some people may need to be screened for colorectal cancer at an earlier age,” Dr. Prem explains. “Particularly if you've got a family history of colorectal cancer, then screening should begin at the age of 40. Some individuals with a genetic predisposition, such as Lynch syndrome, should start screening in their mid-20s.”
Anyone unsure of which category they fall into, particularly those with a parent or sibling who has had colorectal cancer or polyps, should raise this specifically with their doctor, since a family history of colorectal cancer is an important risk factor.
For those ready to be screened, there are three established screening methods in Singapore, each with a different balance of convenience, accuracy, and what happens if something is found.
The distinction matters as a stool test or CT colon scan can flag that something may be wrong, but only a colonoscopy can act on that finding in real time. Colon polyps can be discovered, removed, and sent for analysis within a single appointment.
The argument for colonoscopy rests on an important statistic that Dr. Prem explains succinctly, “If you have a colonoscopy for colorectal cancer screening, and you remove a polyp, it reduces your risk of developing cancer by 70%.”
A colonoscopy is not simply a diagnostic test that tells you whether or not you have cancer. It is actually, in the majority of cases, a preventive procedure in its own right. Removing a polyp during colonoscopy can be the only intervention needed to prevent it from progressing along the 10-to-15-year path toward malignancy. Few other cancer screening tests double as treatment in the same sitting.
Given how much of the screening gap in Singapore is driven by fear and discomfort rather than access, understanding exactly what a colonoscopy involves is often the most useful step toward actually booking one.
When laid out step by step, the procedure seems considerably more routine than the anxiety surrounding it might suggest. For most patients, the preparation tends to be the most demanding part, with the procedure itself taking place under sedation and is typically completed within half an hour.
Colorectal cancer's defining feature is also its greatest weakness as a disease: it takes years to develop, it is detectable well before it becomes dangerous, and the same procedure used to find it can very often remove the threat entirely. The obstacle between Singapore's current 33% screening rate and a lower colorectal cancer burden is not a lack of effective tests, but hesitation.
“If you're over the age of 50, and you've never had a colonoscopy, don't delay any further,” Dr. Prem stresses. “Speak to your doctor about getting a colonoscopy done. Get tested. Get the cure.”
